Middle components of the auditory evoked response in bilateral temporal lobe lesions. Report on a patient with auditory agnosia.

An investigation of the middle components of the auditory evoked response (10--50 msec post-stimulus) in a patient with auditory agnosia is reported. Bilateral temporal lobe infarctions were proved by means of brain scintigraphy, CAT scanning, and regional cerebral blood flow measurements. The middle components were found to be normal regarding latency (pa approximately 30 msec) and configuration of the recordings, when evaluated relative to the peripheral hearing loss in the patient and to the corresponding normative template. Based upon the combined procedures, it is concluded that the middle components cannot be generated exclusively, if at all, in the primary auditory cortex, located in the temporal lobe. Furthermore, the responses are found to be of neurogenic origin according to the methodological procedure applied.